1. Field of the Invention
The invention relates to a strip matter cutting device for sewing machine which is used in, for example, a sewing operation in which a strip matter, such as a tape or rubber, is sewed on the shoulders of a T-shirt and the strip matter is then cut.
2. Description of the Prior Art
As shown in FIG. 9, in sewing the shoulders of a tubular T-shirt S while sewing a tape T on the outside thereof, being generally called "shoulder taping sewing," it is most suitable to use a vertical barrel special bed sewing machine M shown in FIG. 8. The shoulder taping sewing by using the bed sewing machine M can employ the following two manners which are generally called "shoulder taping feed sewing" and "shoulder taping delivery sewing", respectively.
In the former manner, an arm hole S1 of the T-shirt S is fed one after another in a direction of from front to rear of a special cylinder bed B of the bed sewing machine M, and they are allowed to pass through a pressure foot P and a sewing part H for taping sewing. When the special cylinder bed B is full with a plurality of the T-shirts S, sewing operation is interrupted and the pressure foot P is lifted. Then, a tape T extending continuously across the T-shirts S at their shoulders is cut with scissors, while taking out the separated T-shirts S along the special cylinder bed B by pulling them toward its front. After the T-shirts S are all removed from the special cylinder bed B, other T-shirts S are subjected to the foregoing steps, thus repeating this taping sewing.
In the latter manner, a pressure foot P of a vertical barrel special bed sewing machine M, the feed direction of which is the reverse of that of the aforesaid sewing machine, is firstly lifted and a plurality of T-shirts S to be taped are pushed, through an arm hole S1, into the rear of the a special cylinder bed B as many as possible, and then held there. The T-shirts S are continuously delivered one by one along the cylinder bed B to its front, such that they are allowed to pass through the pressure foot P and a sewing part H for taping sewing. When the T-shirts S are all subjected to the taping sewing, sewing operation is interrupted, and a tape T extending continuously across the T-shirts S at their shoulders is cut with scissors. Thereafter, other T-shirts S are subjected to the foregoing steps, thus repeating this taping sewing.
As a cutting device for strip matter, e.g., a shoulder tape, there is known a device employing a conventional construction as shown in FIGS. 10 and 11. In this device, a throat plate 52 having a needle location 51 is secured on the top surface of a sewing machine bed (not shown), and a stationary blade 53 and a movable blade 54 are provided on the rear of the throat plate 52 in the sewing direction (the direction indicated by arrow a in FIG. 10). The movable blade 54 is pivoted such that it is free to shift, via a rotary cylinder 55 or the like, between a standby position at which the movable blade 54 is spaced above the stationary blade 53 as indicated by a dotted line in FIG. 11, to allow for the passage of a tape, and a cutting position at which the movable blade 54 cuts the tape in cooperation with the stationary blade 53 by rocking downwardly as indicated by a solid line in FIG. 11.
As a modification of the cutting device shown in FIGS. 10 and 11, there are also known ones employing the construction disclosed in Japan Patent Publication No. 60-48195 (1985), Japan Utility Model Publication No. 7-5824 (1995), and Japan Patent Publication 2-17195 (1990). None of these are used with a vertical barrel special bed sewing machine, but they are used with a flat bed type covering chain stitch sewing machine (not shown), or a lateral bed type covering chain stitch sewing machine M1 in which a cylinder bed B1 projects from a sewing machine arm A in a lateral direction orthogonal to the sewing direction a, as shown in FIG. 12.
Of the above conventional techniques, in a case where a vertical barrel special bed sewing machine is used and a tape is cut with scissors, because of particularity in the shape of its sewing machine bed, it is necessary to select one of which rotating speed is generally low. In addition, when a taping sewing is terminated, the tape is cut with scissors by the operator. As a result, not only work efficiency is low as a whole, but also it is liable to cause variations in the length of tape cutting allowance, thus increasing tape losses which can be generated in sewing start and stop portions. Although the tape losses is reduced by adjusting the pitch of a continuous feed and delivery of T-shirts S, tape cutting with scissors imposes on the operator's wrist a considerable burden and exhaustion, thereby the operator might suffer from peritendinitis. This is unfavorable from the point of view of health care.
On the other hand, the cutting device for tapes and the like, as shown in FIGS. 10 to 11, or disclosed in the Publication No. 60-48195, can be readily attached to an existing sewing machine without need for a special reconstruction therefor, so that a tape or the like is cut mechanically and automatically. This imposes on the operator less work burden and thus avoids suffering from peritendinitis. However, since distance L from the needle location 51 to the cutting position is long (see FIG. 10), the tape losses caused in the sewing start and stop portions becomes considerably greater than that in the cutting with scissors as described.
In the cutting device for tapes and the like disclosed in the Publication No. 7-5824, the cutting position is set to a point immediately behind a pressure foot. Therefore, this device permits a further reduction in tape losses than the device of FIGS. 10 to 11, and that of the Publication No. 60-48195. It is, however, necessary to reconstruct a throat plate, a throat plate mount and a stationary blade so as to have a special construction. Thus it is unavoidable to increase the cost of the overall device.
In addition, the device of FIGS. 10 to 11, and those of the Publications No. 60-48195 and 7-5824 have the same problem that when they are used in sewing a wide object, a cutting part itself at which a tape or the like is cut may obstruct passage and movement of the object, failing to perform a predetermined sewing operation. This problem is, however, unsolvable even if such a cutting device is attached to a vertical barrel special bed sewing machine.
In the cutting device of the Publication No. 2-17195, since the cutting position is set to a point immediately behind a pressure foot in common with the Publication No. 7-5824, tape losses can be reduced. However, since its cutting blade moves down linearly from obliquely upward of a throat plate to the throat plate immediately behind the pressure foot, there is needed such a special improvement in construction that a stationary blade to be cooperated with the cutting blade is attached to the throat plate. Although the cutting device of the Publication No. 2-17195 can be also used with a vertical barrel special bed sewing machine, there is needed such an improvement in construction that a stationary blade is attached to the throat plate. Further, strength and durability problems can arise because a generally slender barrel cylinder bed part is subject to a strong impact due to the linear movement of the cutting blade.